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Data blocks and Oracle performance - Quiz

Each question is worth one point. Select the best answer or answers for each question.
 
1. Which of the following are true about the PCTFREE parameter?
Please select all the correct answers.
  A. PCTFREE reserves space on the data blocks for row expansion.
  B. Too small a value for PCTFREE may result in chained rows, causing excessive I/O.
  C. PCTFREE is used to trigger a freelist re-link operation of the data block.
  D. The PCTFREE parameter only applies to table that may have column values expanded with UPDATE SQL.

2. What are some signs that an index may benefit from re-building?
Please select all the correct answers.
  A. A large number of deleted leaf nodes
  B. Excessive index splitting
  C. Excessive index spawning
  D. A high value for block gets per access

3. When will reducing the high water mark for a table improve performance?
Please select the best answer.
  A. For index range scans after a large number of rows have been deleted
  B. For any full-table scans
  C. For index range scans that use multi-block reads
  D. For full-table scans after a large number of rows have been deleted